Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may...
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Transcript of Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may...
![Page 1: Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may be represented by a pair of dots, or by a single line.](https://reader036.fdocuments.net/reader036/viewer/2022083004/56649e245503460f94b1289b/html5/thumbnails/1.jpg)
Drawing Organic Structures• Organic compounds are held together by
covalent bonds
• a covalent bond may be represented by a pair of dots, or by a single line
![Page 2: Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may be represented by a pair of dots, or by a single line.](https://reader036.fdocuments.net/reader036/viewer/2022083004/56649e245503460f94b1289b/html5/thumbnails/2.jpg)
Molecular formula
• Use methane as an example
• CH4
– molecular formula– shows relative numbers of atoms– conveys no sense of structure or bonding– conveys no sense of chemistry
![Page 3: Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may be represented by a pair of dots, or by a single line.](https://reader036.fdocuments.net/reader036/viewer/2022083004/56649e245503460f94b1289b/html5/thumbnails/3.jpg)
Writing Molecular Formulas• The number of carbon atoms is specified first• The number of hydrogen atoms is specified next• The remaining atoms are then specified in (usually
alphabetical) order– cyclohexane: C6H12
– benzoic acid: C7H6O2
– ethyl para-aminobenzoate: C9H11NO2
– picryl chloride: C6H2ClN3O6
![Page 4: Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may be represented by a pair of dots, or by a single line.](https://reader036.fdocuments.net/reader036/viewer/2022083004/56649e245503460f94b1289b/html5/thumbnails/4.jpg)
Full structural formula
• every atom specified• every bond explicitly shown
– methane is simple– two structures convey the same information
about as efficiently
C
H
H
HHC
H
H
H
H
![Page 5: Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may be represented by a pair of dots, or by a single line.](https://reader036.fdocuments.net/reader036/viewer/2022083004/56649e245503460f94b1289b/html5/thumbnails/5.jpg)
Now lets try it with cholesterol as the example…
• Molecular formula– C27H46O
![Page 6: Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may be represented by a pair of dots, or by a single line.](https://reader036.fdocuments.net/reader036/viewer/2022083004/56649e245503460f94b1289b/html5/thumbnails/6.jpg)
Full structural formula
C
C
C
C
C
C
C
C
C
C C
C
C
C
C
C
C
C
C
C
CC
CC
C
O
C
C
HH
HH
H H
HH
H H
H
H
HH
H H
HH
HH
H HH
H
H
H
H H
H HH
H
HH
H
H H H
HH
HH
H
HH
H
![Page 7: Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may be represented by a pair of dots, or by a single line.](https://reader036.fdocuments.net/reader036/viewer/2022083004/56649e245503460f94b1289b/html5/thumbnails/7.jpg)
How do we simplify this?• recognize that every organic compound contains
carbon• delete the symbol for carbon atoms except for
those explicitly involved in a functional group (CHO, COOH, CN)
![Page 8: Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may be represented by a pair of dots, or by a single line.](https://reader036.fdocuments.net/reader036/viewer/2022083004/56649e245503460f94b1289b/html5/thumbnails/8.jpg)
Lets do it…
O
HH
HH
H H
HH
H H
H
H
HH
H H
HH
HH
H HH
H
H
H
H H
H HH
H
HH
H
H H H
HH
HH
H
HH
H
![Page 9: Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may be represented by a pair of dots, or by a single line.](https://reader036.fdocuments.net/reader036/viewer/2022083004/56649e245503460f94b1289b/html5/thumbnails/9.jpg)
Can we make it simpler…?• We have removed all the carbon symbols
(every organic compound contains carbon)
• Practically every carbon compound contains hydrogen– delete symbol for hydrogen except where it is
part of a functional group (e.g. CHO, OH)
![Page 10: Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may be represented by a pair of dots, or by a single line.](https://reader036.fdocuments.net/reader036/viewer/2022083004/56649e245503460f94b1289b/html5/thumbnails/10.jpg)
Lets try that…
• Dramatic simplification– structural features are visible
• three rings
• length and shape of side chains
OH
![Page 11: Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may be represented by a pair of dots, or by a single line.](https://reader036.fdocuments.net/reader036/viewer/2022083004/56649e245503460f94b1289b/html5/thumbnails/11.jpg)
Lets try that…
• Dramatic simplification– structural features are visible
– functional groups are visible• OH group of alcohol
• C=C double bond
OH
![Page 12: Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may be represented by a pair of dots, or by a single line.](https://reader036.fdocuments.net/reader036/viewer/2022083004/56649e245503460f94b1289b/html5/thumbnails/12.jpg)
Lets try that…
• Dramatic simplification– structural features are visible – functional groups are visible– information is more available
• how long does it take to find the important features?
OH
![Page 13: Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may be represented by a pair of dots, or by a single line.](https://reader036.fdocuments.net/reader036/viewer/2022083004/56649e245503460f94b1289b/html5/thumbnails/13.jpg)
The molecules of this experiment
• cyclohexane
– C6H12
• toluene
– C7H8
• benzoic acid
– C7H6O2
• ethyl para-aminobenzoate
– C9H11NO2
CH3
CO
O H
NH
H O
O C2H5
![Page 14: Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may be represented by a pair of dots, or by a single line.](https://reader036.fdocuments.net/reader036/viewer/2022083004/56649e245503460f94b1289b/html5/thumbnails/14.jpg)
Properties
• all electrically neutral
• all soluble in non-polar solvents (e.g. ether)
• none soluble in water to an appreciable degree
• cyclohexane & toluene are liquids
• benzoic acid and ethyl para-aminobenzoate are solids
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Benzoic acid
• a carboxylic acid
• has one acidic hydrogen– weak acid
– only slightly ionized
– pKa ≈ 4
• reacts with base to give benzoate anion and water
CO
O H
CO
O HC
O
O
+ H
CO
O HC
O
O
+ OH + H2O
![Page 16: Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may be represented by a pair of dots, or by a single line.](https://reader036.fdocuments.net/reader036/viewer/2022083004/56649e245503460f94b1289b/html5/thumbnails/16.jpg)
• benzoic acid molecules are converted by strong base into benzoate anions
• benzoate anions are converted by strong acids into benzoic acid molecules
CO
O HC
O
O
OH
CO
O HC
O
O
H3O
![Page 17: Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may be represented by a pair of dots, or by a single line.](https://reader036.fdocuments.net/reader036/viewer/2022083004/56649e245503460f94b1289b/html5/thumbnails/17.jpg)
A comparison• benzoic acid
– neutral, covalent molecules
– soluble in non-polar solvents (e.g. ether)
– almost insoluble in water
• sodium benzoate– sodium cations and
benzoate anions
– almost insoluble in non-polar organic solvents (e.g. ether)
– soluble in water
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Ethyl para-aminobenzoate
• has both ester (neutral) and amine (base) functional groups
• has one basic nitrogen– weak base: gives practically no OH— in water
• reacts with acid to give alkylammonium cation
NH
H O
O C2H5
NH
H O
O C2H5
H3O
NH
H O
O C2H5
H
NH
H O
O C2H5
H
OH+ H2O +
+
NH
H O
O C2H5
![Page 19: Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may be represented by a pair of dots, or by a single line.](https://reader036.fdocuments.net/reader036/viewer/2022083004/56649e245503460f94b1289b/html5/thumbnails/19.jpg)
• ethyl p-aminobenzoate molecules are converted by strong acid into alkylammonium cations
• the alkylammonium cations are converted by strong bases into ethyl p-aminobenzoate molecules
NH
H O
O C2H5
NH
H O
O C2H5
H
H3O
OH
NH
H O
O C2H5
H
NH
H O
O C2H5
![Page 20: Drawing Organic Structures Organic compounds are held together by covalent bonds a covalent bond may be represented by a pair of dots, or by a single line.](https://reader036.fdocuments.net/reader036/viewer/2022083004/56649e245503460f94b1289b/html5/thumbnails/20.jpg)
A comparison• ethyl p-aminobenzoate
– neutral, covalent molecules
– soluble in non-polar solvents (e.g. ether)
– almost insoluble in water
• the alkylammonium salt– alkylammonium
cations and sulfate or chloride anions
– almost insoluble in non-polar organic solvents (e.g. ether)
– soluble in water